Extending the Shortcode

Method 1: Hardcoded

by writing your own plugin file with the function in it. Be sure to replace {func} with your desired function name (will result in the parameter “func” in the shortcode). $meta will be the value of the custom field and $alt the “alt” parameter.

The function should return the text by which the shortcode will be replaced. For example the “_plain” function simply returns $meta or $alt if $meta is empty.

Method 2: In the admin panel

This method is more convenient. You can add new functions in the admin panel. For this go to the options page called "Meta Functions Shortcode".
Here you can enter a new function name, specify parameter names and set the output html code with the parameters.

Example:

Function Name: link

Function Parameter Names: link_url, link_caption

Function Result Code: <a href='{link_url}'>{link_caption}</a>

If you now enter the shortcode [meta func="link" link_url="download_url" link_caption="download_caption"] then in the article/page
it will be replaced by <a href='contents of custom field download_url'><i>contents of custom field download_caption</i></a>.